Google Groups is one of the services that would benefit a lot from an integration with Google Calendar, Google Docs, Google Sites and other Google apps. “Now, sharing calendars, sites and documents with multiple people is easier by simply share with an entire Google Group. As an example, imagine you're organizing a local intramural softball team tournament. You use Google Docs to keep track of the rosters for each team as well as each team's performance. You want all the players, but only the players, to’ve editing access. You already’ve a Google Group set up with the tournament participants, so you simply share the spreadsheet with the group itself, granting the group members permission to edit,” said Google blog. To share a document, a calendar or a site, use the group's email address (firstname.lastname@example.org) in the sharing dialog. And if you want to unsubscribe from a group, Gmail makes it easier by adding an "unsubscribe" option when you click on "show options".